Simple and rapid determination of biogenic amines in fish and fish products by liquid chromatography-tandem mass spectrometry using 2,4,6-triethyl-3,5-dimethyl pyrylium trifluoromethanesulfonate as a derivatization reagent.

A simple and rapid analytical method was developed for determination of four biogenic amines [histamine (Him), cadaverine (Cad), tyramine (Tym), 2-phenylethylamine (Pea)] in fish and fish products. This method uses a new derivatization reagent, 2,4,6-triethyl-3,5-dimethyl pyrylium trifluoromethanesulfonate (Py-Tag). The four biogenic amines in the samples were extracted with trichloroacetic acid. The diluted extract was derivatized with Py-Tag (15 min at 50°C) and then subjected to liquid chromatography-tandem mass spectrometry (LC-MS/MS). The limits of quantification for the method were 2 mg/kg for Him, Tym, and Pea and 10 mg/kg for Cad. The matrix effects derived from the tested fish and fish products were negligible in the LC-MS/MS analysis. The impact of the sample matrices on the Py-Tag derivatization was also negligible. The trueness and repeatability of the method were assessed by performing replicate analyses (n = 5) of five samples of fish and fish products, each spiked with the four biogenic amines at three different concentration levels. Analysis of the samples found 87%-104% of the spiked concentrations and the relative standard deviations were <6.1%. A reference sample and quality control canned fish samples were analyzed by the method, and the concentrations of the Him were within acceptable limits. The developed method was successfully used to determine concentrations of the four biogenic amines in 48 fish and fish products on the Japanese market. The developed method does not require cleanup using a solid-phase extraction column or similar, and the derivatization reaction time was only 15 min. The results suggested that the present method is reliable and suitable for rapid analysis of the four biogenic amines in fish and fish products.

Development of an analytical method for determination of total ethofumesate residues in foods by gas chromatography-tandem mass spectrometry.

Analytical method was developed for determining the total residue of ethofumesate (ET) herbicide using GC-MS/MS. The ET residues were analyzed as a sum of ET, 2-keto-ethofumesate (KET), and open-ring-2-keto-ethofumesate (OKET) and its conjugate. The extracted samples were partitioned with hexane and NaOH solution. For ET analysis, the hexane layer was cleaned up by a silica gel cartridge prior to GC-MS/MS analysis. For the analyses of the metabolites, the aqueous layer was heated with HCl to hydrolyze the conjugates, thereafter, heated in acetic anhydride to convert OKET to KET, and cleaned up by a silica gel cartridge prior to GC-MS/MS analysis. The method was validated for ET, KET, and OKET in garlic, onion, and sugar beet at 0.3 and 0.01 mg/kg. The recoveries were 94-113%, with relative standard deviations of <6%. The limits of detection were 0.0005 mg/kg for all analytes. The proposed method is suitable for regulatory analysis.

Determination of total florfenicol residues as florfenicol amine in bovine tissues and eel by liquid chromatography-tandem mass spectrometry using external calibration.

A reliable liquid chromatography-tandem mass spectrometry method was developed to determine total florfenicol residues in bovine tissues and eel. Florfenicol and its metabolites (florfenicol amine, monochloroflorfenicol, florfenicol oxamic acid, and florfenicol alcohol) were analyzed as the marker residue, florfenicol amine, as defined by several regulatory agencies. After hydrolysis with hydrochloric acid, samples were defatted and subjected to solid-supported liquid extraction and Oasis MCX-cartridge cleanup before analysis. The method was validated for florfenicol and its metabolites at two levels in eel and bovine muscle, fat, and liver. Excellent recoveries were obtained (93-104%), with relative standard deviations of <6% for all compounds. Negligible matrix effects and minimal analyte loss during sample preparation enabled accurate quantification by external calibration using solvent standards. No interfering peaks were observed around the retention time of florfenicol amine, indicating the high selectivity of the method. Retention times in the spiked samples corresponding to that of the calibration standard in solvent did not exceed ±0.1 min. Ion ratios from the spiked sample were within ±10% (relative) of the calibration standards. Calibration curves were linear in the range of 0.5 to 100 ng/mL, with coefficients of determination higher than 0.998. The limits of quantification and limits of detection of the proposed method were estimated to be 0.01 mg/kg and 0.0005 mg/kg, respectively, in all food samples. Thus, the developed method is considered reliable and suitable for regulatory use.